Insulating inorganic metal oxide materials, such as ferroelectric materials or perovskite material, have high dielectric constants and low current leakage which make them attractive as cell dielectric materials for high density DRAMs and non-volatile memories. Perovskite material and other ferroelectric materials exhibit a number of unique and interesting properties--both physical and electrical. The defining property of a ferroelectric material is that it possesses a spontaneous polarization that can be reversed by an applied electric field. Specifically, these materials have a characteristic temperature, commonly referred to as the transition temperature, at which the material makes the structural phase change from a polar phase (ferroelectric) to a non-polar phase, typically called the paraelectric phase.
Despite the advantages of high dielectric constants and low leakage, insulating inorganic metal oxide materials suffer from many drawbacks. One major hurdle to incorporating perovskites into semiconductor processing methods is the fact that no reliable method for dry etching such materials exists. The major problem is that most of the inorganic compounds formed are solids having high boiling temperatures. In other words, the conventional dry etching of perovskite material results in formation of solid compounds, as opposed to gaseous compounds as in dry etching techniques for other materials which are then easily expelled from the wafer. For example, dry etching of perovskite materials containing barium of strontium typically produces chloride, such as BaCl.sub.x, SrCl.sub.x, and TiCl.sub.4. Only the latter of these is volatile under typical semiconductor wafer processing conditions.
Accordingly, there remains a need for development of semiconductor wafer processing methods enabling use of insulating inorganic metal oxide materials as capacitor materials involving dry etching processes for such insulating inorganic metal oxide materials.